1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to managing asynchronous interference.
2. Introduction
A wireless communication system may implement an interference management scheme to mitigate interference caused by neighboring wireless devices. For example, in a cellular system wireless transmissions of a cell phone or a base station of a first cell may interfere with communication between a cell phone and a base station of a neighboring cell. Similarly, in a Wi-Fi network, wireless transmissions of an access terminal or an access point of a first service set may interfere with communication between an access terminal and a base station of a neighboring service set.
A synchronous communication system may use synchronous interference management messages to control interference on a given channel. Here, the wireless devices in the system may transmit such messages or monitor for such messages at designated times within certain timeslots on the channel. Thus, a wireless device that is receiving data during an upcoming timeslot may transmit a message to request that potential interferers abstain from transmitting during that timeslot. Conversely, a potential interferer may monitor the channel at the designated times to determine whether it should abstain from transmitting during an upcoming timeslot. Although such a scheme may be effective for controlling interference between devices that are synchronized with one another, such a scheme may be ineffective in controlling interference between wireless devices that are not synchronized. For example, in such a case, a potential interferer may not be monitoring the channel when another device is transmitting its interference management messages.
An asynchronous communication system may employ techniques such as carrier sense multiple access to control interference on a given channel. In this case, before transmitting on the channel, each wireless device may verify that the channel is not being used by any other wireless device. In practice, however, such interference mitigation techniques may lead to poor utilization, limited fairness control, and susceptibility to hidden and exposed nodes.